Extreme rainfall in south and south west of Iran and its association with Atmospheric Rivers (ARs)

Atmospheric rivers (ARs) are long narrow band of high water vapor flux that closely related to heavy rainfall. Flooding from heavy rainfall is one of the major hazards in south and south west of Iran. In this paper, the connection between ARs and heavy rainfall is analyzed by a methodology based on the vertically integrated water vapor transport (IVT). Heavy rainfall days are identified from the Iran Meteorological Organization (IRIMO) from 1987 to 2019. Our results suggest that, all inclusive heavy rainfall events over the south and southwest of Iran are associated with the contributions by the ARs and they matches tend to peak in the cool season. Larger IVT value in the region related to more precipitation and play important role in determining the amount of it. The IVT value intense when the AR crossed over the region. According to the results, there were four major sources of ARs that effected on south and south west of Iran generally include Gulf of Aden, the Red Sea, Arabian Sea and Soudan. The Red Sea is the most important source of moisture those intense ARs on their path in this region.